As soon as a woman sees two stripes on a pregnancy test, the question almost immediately arises of when to expect an addition to the family. The date of birth is a landmark that helps a woman to more effectively plan the remaining time, prepare for the birth of a baby, make adjustments in her life, complete repairs in the apartment by this time and make all the necessary purchases. Determining the due date is a delicate and nuanced process.
What is DAA?
This abbreviation is familiar to all women who have been pregnant. For expectant mothers, it has almost magical meaning. PDD is the estimated day of birth. Why supposed? Because no one can know the exact date of birth (the birthday of your child). There is no such method of medical diagnostics that could tell exactly when the baby will be born. The only exception to the rule is a planned caesarean section, but even in this case, the date of the operation is usually set up to date shortly before delivery. The rest of the time, the woman's card also has a PDD.
The estimated day of delivery is the last day of the 40th week of pregnancy, its completion. It is considered approximate guideline for the expectant mother and doctors. In practice, a child can be born on any other day. between 38 and 42 weeks, and that will be - perfectly normal.
According to statistics, exactly on the day of PDD, only about 5% of babies are born.
Childbirth is a complex physiological process, in which all systems, hormones, muscles and tissues are involved, and therefore childbirth will begin when the mother and baby are ready for this. There is not a single method in the world that would allow predicting when that day will come.
Nevertheless, this date was chosen as the base - the last day of the 40th week, possibly because this is the arithmetic mean of the entire range of possible delivery in term (term delivery).
How to count?
You can determine and calculate the estimated day of birth by several methods, both independently and using a convenient online calculator. The calculation algorithm is the same in both cases. It is based on the obstetric method of determining the timing - by the date of the last menstruation.
The only thing that is needed for this is remember correctly the date when your last menstrual period started.
Many women are confused and call not the date of the first day of the last menstrual bleeding, but the last day of menstruation, this is incorrect. It is the first day when menstruation began, which opened the cycle in which conception took place, that is important.
Why is this date important? This is easier than it sounds. In medical practice, it is considered to be the first day of pregnancy. It may seem absurd, but this is the most accurate method. The fact is that you can conceive a baby only on the day of ovulation and within 24–36 hours after it. Then the egg cell dies, the onset of pregnancy becomes impossible. But it can be difficult to establish the date of ovulation. It depends on numerous complex hormonal processes in a woman's body, and therefore it can be both early and late. The gold standard is ovulation, which occurs 14 days before the end of the cycle.
Sperm cells can reach the egg on the day of ovulation if sex took place on that day. But also male germ cells, due to their natural vitality, can exist in the genital tract of a woman for several days and fertilize an oocyte even after they have been waiting for 3-5 days. If a woman is healthy, young, has an active sex life, has sex regularly, to establish what kind of sexual intercourse led to conception, and when it actually took place up to the day, there is no possibility at all - there are too many unknowns in one equation. Therefore, they take as a basis the only meaning that is not in doubt and known for sure - the day when the last menstruation began.
There are several obstetric formulas for calculating PDD by the date of the last menstruation:
- (date of the last monthly + 9 calendar months) - 7 days;
- (date of last menstruation - 3 months) + 7 days;
- date of last menstruation + 280.
Which of the formulas to use is up to you. Even obstetricians-gynecologists use different formulas, and most often they do not consider anything at all - they have a special obstetric calendar, round, with shifting windows, which also indicates the PDD, if you set the date of the last menstruation.
An online calculator is much more convenient. He counts in the same way, only quickly: in seconds after entering the date, month and year of the date of the last menstruation, the program shows the PDD, and additionally - the estimated day of conception, the current period with an accuracy of the week and day, and at the same time offers useful links to articles about your the current period, about how the baby is developing, what physiological changes occur in the body of the expectant mother.
How to count with an irregular cycle and after IVF?
The duration of the menstrual cycle does not matter for calculating the date of birth. The main thing is that the woman remembers the date of the beginning of the last menstruation. If she does not remember this day, then the existing obstetric formulas cannot be used.
Usually, in this case, an ultrasound scan is performed at an early stage, which allows you to establish the PDR depending on the current period in terms of the size of the ovum and the CTE - the coccygeal-parietal size of the fetus.
After IVF, existing methods and calculators are also inapplicable. The in vitro fertilization procedure differs from natural conception in that the fusion of the germ cells occurs in a laboratory, and the doctors know the exact date of conception. Moreover, embryos can be transferred to the uterus on different days, at different embryonic ages; previously frozen embryos can also be used in a cryoprotocol.
therefore there are calculators that allow you to calculate the PDR after IVF. You need to enter two values into them - the date of transfer (replanting) of embryos and their embryonic age at the time of transfer (4-day, 5-day or 6-day). The result is also displayed in obstetric time.
Alternative counting methods
There are also auxiliary or alternative ways to calculate the date of birth, but they are not widely used due to their lower accuracy.
By ovulation, conception
The method assumes that the woman knows exactly the date of her ovulation. This is usually possible only with controlled ovulation, when the process of follicle maturation and rupture of the dominant membrane were provoked in the treatment cycle by hormonal agents.
In this case, the follicles are constantly monitored by ultrasound, and the day of ovulation is known to the doctor with an accuracy of up to a day. 280 should be added to this date - this will be the embryonic date, which will determine the date of birth.
Some people try to calculate the due date from the date of conception. This is not much different from the method described above, because, as we know, conception occurs only during ovulation. But an error of 1–2 days is already automatically implied.
By the movements of the fetus
When ultrasound did not exist, this method was the only one with which the doctor could confirm his mathematical calculations and clarify the DA. It is believed that primiparas begin to feel the first movements of the baby at 20 weeks, and multiparous - at 18 weeks. In this way, in the first case exactly 20 weeks are added to the date of the first stirring, and in the second - 22 weeks.
The method can hardly be called accurate, since a lot of questions and difficulties arise with the definition of the first movements, especially among pregnant first-borns - they are often confused with the fermentation of gases in the intestines, and therefore the exact day of the first movement often goes unnoticed.
Ultrasound
Ultrasound examination to establish the duration of pregnancy and PDD most effective only in the early stages - up to 10-12 weeks of pregnancy. Then a big error appears. The fact is that embryos grow at approximately the same rate, and while the processes of embryogenesis are going on, the development of all babies is almost the same.
Then, when all organs and systems are formed, the fetal period begins, during which the fetus grows and gains weight. And he will do this according to his personal genetic program, which he inherited from his parents: some children are tall, others are low; some have more weight, others less, and therefore children of the same gestational age may differ in fetometry parameters.
The gender of the baby also matters - boys usually grow a little faster in the womb than girls. And it becomes difficult to establish the gestational age.
Personal characteristics of the cycle and pregnancy
When compiling a pregnancy calendar by weeks, calculating the date of birth, a woman should remember that her menstrual cycle is unique, one of a kind, which can also leave an imprint on the date of birth.
Usually women with a standard, classic cycle of 28 days give birth at or close to the PDD term. The first-borns are also born close to the DA.
If a woman's cycle has always been 32, 33 or more days, then the expected due date, as a rule, is shifted to a later date - these are the biorhythms of the body of a particular woman. In this case, childbirth often occurs at 41-42 weeks and at a later date. Pregnancy with a large fetus is also often prolonged to this period.
Women with short cycle times (less than 26 days) usually give birth earlier than PDD. At 38–39 weeks, up to 70% of repeated births usually occur. Childbirth after IVF most often occurs before the PDD, as well as childbirth with multiple pregnancies.
